Which best explains why a pyramid is used to represent energy flow within an ecosystem? Hint: what happens to available energy as you go up?

1. Because available energy decreases as you go up

2. Because the organisms get bigger

3. Because the amount of the organism is more

4. Because further of organisms use less energy

Indicate the coat color and the proportion of offspring with that color for each of the following crosses of rabbits. assume all are homozygous. chinchilla x chinchilla 1/2 agouti, 1/2 chinchilla 3/4 agouti, 1/4 chinchilla all chinchilla

How much time has elapsed from the very beginning of "the memior of the conquistador bernal diaz del castillo" to the end? a. castillo's whole life b. a quarter of an hour c. a few weeks d. a decade

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.